The present invention relates to a multiprocessor system having a plurality of processor elements, and relates, for example, to a technology that is effective when being applied to an ECU (electronic control unit) for vehicle, a microcomputer for an ECU, or the like for which functional safety is necessary and operation continuity is to be considered.
Along with electrification of cars in recent years, requests for functional safety and operation continuity have been intensified. That is, there are intensified requests for functional safety (fail-safe) such as performing communication before the generation of abnormality in a controller to thereby prevent accidents beforehand, or continuing an operation even when abnormality occurs to thereby allow the movement of the car to a repair shop possible. As technologies corresponding to fail-safe, conventionally DLS (Dual Lock Step) and TMR (ternary majority rule) are provided. In DLS, for example, two processor elements that perform the same data processing are tightly coupled and operated, the operation results are compared one by one, the data processing is continued on the condition that the comparison results are the same, the determination of abnormality is made when the comparison results do not coincide with each other, and thus a changeover or the like to an alternative device is performed. As an example of a literature in which DLS is described, there is Japanese Patent Laid-Open No. 2013-242746.
TMR is a technology of tightly coupling three processor elements, making a comparison one by one among the output from respective processor elements one by one, and applying the majority rule to non-coincidence, to thereby be made relievable even when one processor is in an abnormal state. As an example of a literature in which TMR is described, there is Japanese Patent Laid-Open No 1996-278898.